Retail outlets for frozen confectionery typically store the frozen confectionery in a freezer. Such freezers are essentially the same as domestic freezer appliances, having a chamber in which the frozen confectionery is stored, which is chilled by refrigeration apparatus.
Most frozen confectionery products are to be stored within narrow temperature ranges, in order to maintain product quality. However one drawback of such freezers is that they tend to suffer from large temperature gradients. Such temperature gradients are established due to fact that warm air is less dense than cold air and also because the majority of the heat ingress occurs through the upper surface of the chamber, as the walls and base are typically thermally insulated.
Often this temperature gradient is merely tolerated, and large temperature differences can exist between the average product temperature and the coolant to compensate the heat entering the cabinet through the lid. Additionally in order to ensure that the maximum allowable product temperature is not breached, the refrigeration temperature needs to be set much lower than the temperature of the products, especially those near the surface of the chamber.
Alternatively, steps can be taken to circulate the air within the freezer to ensure turbulent mixing of air, e.g. by installing ventilator fans, and thus eliminating the temperature gradients within the freezer by bulk movement of air. This can provide a homogeneous temperature within the freezer. However, even though the freezer can be operated closer to the maximum tolerance temperature than in the stagnant case, this surprisingly comes at the cost of increased energy consumption. This is due firstly to the energy requirement of agitating the air, and secondly because the bulk flow of the air near the surface of the freezer increases the rate of transport of heat through the surface, increasing the load on the refrigeration unit.
Thus improvements in the operation of such freezers would be highly desirable.